1. Field of the Invention
The present invention relates to a device for catalytic treatment of a gas flow comprising (including, but not limited to) at least one body which includes a catalytic material. The device has a number of first openings for either entry of gas into, or exit of gas from, the catalyzer body. A second opening is provided for either the exit of the gas entering through the first openings, or entry of gas into the catalyzer body for subsequent exit through the first openings. The first openings are open outward, from the catalyzer body, on a portion of the body at a distance from a first delimiting surface thereof, toward which delimiting surface the body is adapted to guide at least some of the incoming gas.
In all combustion of hydrocarbon fuel, for example petrol and diesel oil, exhaust gases are formed. Such exhaust gases include uncombusted or partially combusted fuel thereby establishing a mixture that includes hydrocarbons (HC), carbon monoxide (CO), carbon dioxide (CO2) and water. Nitrogen gas and oxygen also combine to form nitrogen oxides (NOx).
In a catalytic device, the aim is to supply oxygen to the carbon monoxide of the exhaust gases so that carbon dioxide is formed, and to supply oxygen to the uncombusted hydrocarbon so that it is combusted completely to form carbon dioxide and water. Furthermore, it is desirable to remove oxygen from the nitrogen oxides so that molecular nitrogen is formed.
It is possible to bring about such reaction(s) by means of a device in which the gas is brought into contact with a catalytic material. This reaction also takes place at lower temperatures, but is in the main set going at a certain elevated temperature, usually roughly 300° C.
2. Background Art
Devices for catalytic treatment of a gas flow are usually referred to as catalyzers and are previously known. For catalytic treatment of exhaust gases from a vehicle, the device can be arranged directly after the cylinders of the internal combustion engine. The branch pipes from the cylinders can then be brought together at a junction, and a common pipe for the gases connects the junction to the catalytic device. A disadvantage of such devices is that the pressure pulse from one cylinder can penetrate another cylinder during the gas exchange phase, a characteristic associated with power and efficiency losses.